Method and apparatus for network-based admission control using path-coupled quality of service signaling

ABSTRACT

A Resource ReSerVation Protocol (RSVP) proxy is used in combination with a signaling proxy to provide improved admission control, Quality of Service (QoS) reservation, and media path routing. This avoids entangling call signaling with media plane functions as required with Session Border Controllers (SBCs). A QoS access network control scheme, such as Packet Cable Multi-Media (PCMM) and/or Dynamic Quality of Service (DQoS), is conventionally used to set up QoS and other flow states on an access network. However, the gate parameters established during this access operation are also provided to an RSVP proxy in an edge router. The gate parameters trigger the RSVP proxy to attempt to establish a QoS reservation over the packet network toward a media flow destination. If admission control for the QoS reservation is successful, the edge router permits the signaling proxy to complete the media call.

BACKGROUND

Internet Service Provider (ISP) networks contain routing and switchingequipment that connect users to other endpoints in the same ISP networkor to endpoints in other ISP networks. Internet Service Providersgenerally do not like users forming end-to-end connections through theirnetworks that cannot be monitored. For example, the ISP network mayinclude firewalls, that need to monitor all incoming connections inorder to prevent unauthorized network access. Other equipment, such asNetwork Address Translators (NATs), may also need to monitor userconnections in order to convert between public and private InternetProtocol (IP) addresses.

Network connections may also need to be continuously monitored in orderto diagnose network problems. For example, when two endpoints establishan end-to-end session, the ISP has limited visibility to thecommunications transferred between the two users. This may prevent theISP from debugging subsequent network failures.

End-to-end user connections arguably make it more difficult for the ISPto manage Quality of Service (QoS) for different types of data or fordifferent users. With end-to-end connections, the user machinesgenerally have the responsibility for requesting and monitoring QoS.Without ISP system level QoS management, a user may request higher QoSthan is necessary for certain types of media communications. This maydisrupt other media communications that do require high QoS, such as areal-time VoIP phone calls.

The Resource ReSerVation Protocol (RSVP) is a path coupled signalingprotocol that goes from one endpoint to an opposite endpoint and throughevery router between the two endpoints. The routers install statesassociated with the type of service requested by the users. When all therouters along the media path indicate a level of requested service canbe provided, the endpoints are notified that admission control hassucceeded and the reserved media path is then used for transportingmedia.

RSVP is not preferred by many ISPs partly because it typically isinitiated by the users. As mentioned above, it is perceived by the ISPas a loss of control over QoS management. Further, many user hostdevices, such as personal computers, may not implement RSVP, which wouldthen prevent any admission control of QoS service for the media call.

Session Border Controllers (SBCs) are currently being used to managesignaling and media at the edges of ISP networks. The SBC may conductsignaling sanitization that removes certain information from the callsignaling, such as public IP addresses, caller ID information, etc. TheSBC may also modify information, such as converting private IP addressesto a public NAT addresses. The SBC may also modify QoS service bits formedia packets.

If ISPs adopted end-to-end path-coupled admission control signaling,there would be little need for SBC media plane functions. However, asdescribed above, Multiple System Operators (MSOs) require and haveadopted additional QoS control such as provided by Dynamic Quality ofService (DQoS) and Packet Cable Multi-Media (PCMM). This QoS controlutilizes an SBC to provide admission control at multiple points alongthe media path.

In order to do so, the SBC must have topological knowledge of the mediapaths. This is inconvenient, can be a performance bottle-neck andusually results in poor responsiveness to routing changes or outages.

Thus, the SBC is required to sit in both the control path and data pathfor each network flow that requires ISP management. The SBC interceptsall application signaling and inserts itself in both the signaling andthe media path established by the associated application. This requiresthe applications used for establishing media connections to communicatedirectly with the SBCs. For example, a Session Initiation Protocol (SIP)or H.323 signaling session is required to conduct signaling for everyVoIP call through the SBC. In addition to the signaling, the audio datafor the VoIP call must also be routed through the same SBC.

This management architecture causes several problems. For example, whenthe SBC fails, all the media sessions managed by the SBC are terminated.This compromises reliability for the overall ISP network. End-to-endmedia security is also broken, since the SBC requires access to thesession encryption keys in order to manage the data in the mediasession.

When centralized in the ISP network, the SBC becomes a hotspot, sinceall communications needs to be routed through the same node. Inefficientrouting problems remain even when SBCs are distributed out toward theuser access locations. For example, routing algorithms have to bereconfigured to route all communications through the remote SBCs. Thiscauses media to be routed along suboptimal network paths. For instance,instead of using optimized routing algorithms that may establish arelatively direct Internet connection between two closely locatedendpoints, the IP connection may have to be routed through two SBCs thatare located in geographic locations remote from both endpoints. This isnot only inefficient, but may also introduce significant extra delay,which is highly disadvantageous for delay-sensitive applications such asVoIP.

The present invention addresses this and other problems associated withthe prior art.

SUMMARY OF THE INVENTION

A Resource ReSerVation Protocol (RSVP) proxy is used in combination witha signaling proxy to provide improved admission control, Quality ofService (QoS) reservation, and media path routing. This avoidsentangling call signaling with media plane functions as required withSession Border Controllers (SBCs). A QoS access network control scheme,such as Packet Cable Multi-Media (PCMM) and/or Dynamic Quality ofService (DQoS), is conventionally used to set up QoS and other flowstates on an access network. However, the gate parameters establishedduring this access operation are also provided to an RSVP proxy in anedge router. The gate parameters trigger the RSVP proxy to attempt toestablish a QoS reservation over the packet network toward a media flowdestination. If admission control for the QoS reservation is successful,the edge router permits the signaling proxy to complete the media call.

The foregoing and other objects, features and advantages of theinvention will become more readily apparent from the following detaileddescription of a preferred embodiment of the invention which proceedswith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a service provider network that provides improvedmedia call management.

FIG. 2 is a flow diagram showing how a signaling proxy operates in theservice provider network in FIG. 1.

FIG. 3 is a flow diagram showing how an edge router operates in theservice provider network shown in FIG. 1.

FIG. 4 is a diagram showing how a media path can be dynamically reroutedin response to a media path failure.

FIG. 5 is a flow diagram showing how the service provider networkmanages a media call from an external network.

FIG. 6 is a diagram showing how QoS reservation can be performed overdisparate service provider networks.

DETAILED DESCRIPTION

Referring to FIG. 1, a first service provider network 14 includes anedge router 26 that connects to a subscriber 22 through an accessnetwork 20. The access network 20, in one example, may be a DOCSIS-basedHybrid Fiber-coax (HFC) network providing high-speed broadband serviceto consumers and businesses. The subscriber 22 can be any device thatneeds to establish a media connection with another endpoint. Forexample, the subscriber 22 may be a Personal Computer (PC), Voice OverInternet Protocol (VoIP) phone, Analog Terminal Adapter (ATA) device, orany other type of server or processing device that transmits and/orreceives media over an IP network.

The first service provider network 14 includes a border router 36 thatcommunicates over a link 50 with a second service provider network 16.Additional border routers 40 in the first service provider network 14communicate though separate links 52 to the second service providernetwork 16, or to other service provider networks that are not shown inFIG. 1.

The service provider networks 14 and 16 can be any Internet Protocol(IP) packet switched network that includes multiple routers, switches,or other network processing devices that form a portion of the Internet,Wide Area Network (WAN), Metropolitan Area Network (MAN), etc. In oneexample, the individual service provider network 14 is operated by acommon business entity, such as an Internet Service Provider (ISP),Multiple System Operator (MSO) or other business enterprise. It isgenerally the case that the second service provider network 16 isoperated by a different business entity. However, the service providernetworks 14 and 16 are not required to be operated by any particularorganization or entity.

Application intermediaries are used in the service provider network 14for voice and video applications. These intermediaries are generallyreferred to as “signaling proxies” when employed for real-timeapplications such as VoIP or video conferencing. They manage thesignaling for setting up media sessions among subscribers. A quality ofservice manager integral to the signaling proxy is then used forrequesting QoS treatment for particular service flows.

For example, a signaling proxy 30 in network 14 manages call signalingwhen the subscriber 22 initiates or receives a media call. The mediacall can contain any type of media that needs to be transferred betweentwo endpoints, such as, a Voice Over Internet Protocol (VoIP) audiocall, or any other type of streaming video and/or audio, or otherreal-time data transmission. Examples of signaling proxies 30 includeSession Initiation Protocol (SIP) proxies and H.323 proxies/gatekeepers.The SIP proxy and H.323 gatekeeper are described in several Request ForComments (RFC) including RFC 2543 and 3261 which are herein incorporatedby reference.

The signaling proxy 30 receives signaling messages 19 from thesubscriber 22 over a signaling path 18. The signaling proxy 30interprets and then forwards the signaling messages 19 toward adestination endpoint. The signaling messages 19 may traverse severalsignaling proxies on the way to the destination endpoint. For example,the signaling proxy 30 may forward some signaling messages 19 to anothersignaling proxy 44 in service provider network 16. Each signaling proxy30 and 44 may make routing decisions and modify the signaling messages19 before forwarding the call request to a next network processingelement.

In one embodiment, the signaling proxy 30 uses the PacketCableMultimedia (PCMM) protocol over a control path 34 for setting up a QoSstate in the edge router 26. The PCMM protocol is described in CableTelevision Laboratories, Inc. (CableLabs®) PacketCable™ MultimediaSpecification PKT-SP-MM-I02-040930 and RFC 2753 which are both hereinincorporated by reference.

A policy server 32 functions as an intermediary between the signalingproxy 30 and the edge router 26 and applies a set of policy rules thathave been pre-provisioned by the operator of service provider network14. The signaling proxy 30 uses control path 34 through the policyserver 32 to setup media path states in the edge router 26 associatedwith the signaling messages 19. The signaling proxy 30 and policy server32 can operate in the same device or can be separate devices.

In conventional service provider QoS management systems, such as PCMM,QoS state information is pushed from the signaling proxy 30, through thepolicy server 32, to the edge router 26. The edge router 26 then usesthis QoS information to provide QoS over the access network 20 betweenthe subscriber 22 and the service provider network 14. However, theseconventional QoS management systems for access networks do not provideadmission control, QoS control, or identify paths for the media withinthe service provider network 14 or for connection between serviceprovider networks 14 and 16. To resolve these limitations, accessnetwork QoS control is used in conjunction with RSVP proxies.

Extending QoS Over and Between Service Provider Networks

An RSVP proxy 28 is operated in the edge router 26 and RSVP proxies 38and 42 are operated by the border routers 36 and 40, respectively. Theoperation of RSVP proxies 28, 38 and 42 are described in detail in U.S.Pat. No. 6,721,272, issued Apr. 13, 2004, entitled: METHOD AND APPARATUSFOR GENERATING AN RSVP MESSAGE FOR A NON-RSVP-ENABLED NETWORK DEVICE;and in U.S. patent application Ser. No. 10/828,370, filed Apr. 19, 2004,entitled: METHOD AND APPARATUS FOR DYNAMICALLY DETERMINING WHEN TO USEQUALITY OF SERVICE RESERVATION IN INTERNET MEDIA APPLICATIONS which areboth herein incorporated by reference.

RSVP proxies 28, 38 and 42 allow the edge router 26 to initiate RSVP onbehalf of subscriber 22 in accordance with QoS control messages providedby signaling proxy 30. The RSVP proxy 28 determines when a subscriberdata flow requires QoS, and on behalf of the subscriber, initiates anRSVP Reservation Session that secures a QoS provisioned path 35 throughthe service provider network 14. The RSVP proxies also provide admissioncontrol both at edge router 26 and at border router 36.

This enhanced access control scheme combines the QoS protocol used forthe access network 20 (e.g., PCMM/DQoS) with an internal media path QoSprotocol (e.g., RSVP) to provide more effective QoS and admissioncontrol in ISP networks. This provides substantial improvements overexisting session border controller architectures since signaling andmedia paths can now be processed in separate conventional preexistingnetwork processing elements while also allowing the service provider tomanage media calls. Calls also do not have to be rerouted through SBCsthat reside outside the conventional media routing path 24. Subscriberendpoints do not have to originate and terminate RSVP signaling,alleviating the ISP concerns over maintaining control and visibility ofmedia flows. Other advantages of the enhanced access control scheme aredescribed in more detail below.

Referring to FIGS. 1 and 2, in operation 60, the signaling proxy 30receives and analyzes a media call request from the subscriber 22 viasignaling messages 19. In one example, as described above, the signalingmessages 19 may be SIP or H.323 signaling messages and the signalingproxy 30 may be a SIP proxy or H.323 gatekeeper that processes the SIPor H.323 signaling messages 19, respectively.

In operation 62, the signaling proxy routes the signaling messages 19toward the destination endpoint for the call. For example, the signalingproxy 30 may route the signaling messages 19 over signaling path 43 tothe signaling proxy 44 in service provider network 16. This of coursedepends on the destination endpoint identified in the signaling messages19. It is also possible that the media call may be directed to anotherendpoint connected to service provider network 14. In this case, thesignaling proxy 30 may route the signaling messages 19 to anothersignaling proxy in service provider network 14 or directly to thedestination endpoint connected to service provider network 14.

In operation 66, the signaling proxy 30 waits to receive a reply back tothe forwarded signaling messages 19. For example, the signaling proxy 30may wait to receive a reply back from signaling proxy 44 indicating thecall request in signaling messages 19 is successful. If this phase ofthe call signaling is successful, the signaling proxy 30 then exchangesQoS control messages 33 over control path 34 with the RSVP proxy 28 inedge router 26. These QoS control messages 33, such as PCMM or DQoSmessages, identify a requested QoS level for the media call, in additionto the destination address for the call.

In PCMM when the first call signaling message 19 is received, there areinitial control messages 33 exchanged between the signaling proxy 30 andthe policy server 32. Other control messages 33 are also exchangedbetween the policy server 32 and the edge router 26. These initialcontrol messages 33 may only provide for minimal operations, such asallocation of a “gate” and some security checks. Other control messages33 are then exchanged between the signaling proxy 30, policy server 32,and edge router 26 that establish or deny the media call after the RSVPproxy 28 receives a response back over service provider network 14indicating a willingness to accept the call. This is described in moredetail below.

Based on QoS messages 33, received back from the edge router 26, thesignaling proxy 30 in operation 68 determines if the service providernetwork 14 will accept the media call requested by subscriber 22. Theservice provider network 14 may not be able to handle the call, forexample, due to lack of available capacity. In this case, the signalingproxy 30 receives a failure message 33 over control path 34 from theedge router 26. Accordingly, the signaling proxy in operation 72 sends acall failure message 19 back to the subscriber 22 and the call isterminated. When a success message 33 is received from the edge router26 in operation 68, the signaling proxy 30 in operation 70 notifies thesubscriber 22 that the call establishment can proceed. Once the finalphase of call establishment completes, the subscriber 22 can startsending media data over media path 24.

FIG. 3 shows in more detail what happens in the edge router 26 once theQoS messages 33 are received from the signaling proxy 30. In operation80, the edge router 26 receives the QoS control messages 33, such asPCMM messages, from the signaling proxy 30 (via the policy server 32).The edge router 26 in operation 82 first determines if a requested QoSstate identified in the QoS messages 33 is available over the accessnetwork. For example, the edge router 26 may determine if it can handleanother VoIP call that requires a particular QoS level on the accessnetwork 20. If the requested QoS state is unavailable, the edge router26 in operation 90 sends a QoS failure message 33 via control path 34back to the signaling proxy 30. If the media call from subscriber 22 canbe processed, the edge router 26 then performs a second stage of QoS andaccess control.

In operation 84, the edge router 26 determines whether the RSVP proxy 28should be invoked. For example, the QoS messages 33 may containparticular destination and source addresses and other traffic flowattributes for the media call request. These attributes ascertained inoperation 84 are correlated with predetermined relationships and/orlogic to determine whether or not to send an RSVP message 37 toward thedestination for the media call. For example, the edge router 26 does notbother to send RSVP messages if the other subscriber is reachablethrough the same edge router, because no backbone network path would betraversed in this case. Similarly, RSVP might not be initiated if theother subscriber is served by an edge router in the same point ofpresence (POP), because the service provider network has been engineeredto have excess capacity for such cases.

Dynamic determination of whether to invoke RSVP proxy operation may alsobe made by using any of the techniques described in U.S. Pat. No.6,721,272, issued Apr. 13, 2004, entitled: METHOD AND APPARATUS FORGENERATING AN RSVP MESSAGE FOR A NON-RSVP-ENABLED NETWORK DEVICE; and inU.S. patent application Ser. No. 10/828,370, filed Apr. 19, 2004,entitled: METHOD AND APPARATUS FOR DYNAMICALLY DETERMINING WHEN TO USEQUALITY OF SERVICE RESERVATION IN INTERNET MEDIA APPLICATIONS which havealready both been incorporated by reference.

If the edge router 26 does not need to invoke the RSVP proxy 28 inoperation 84, a call success message 33 is sent back to the signalingproxy in operation 92. However, when the RSVP proxy 28 is invoked inoperation 84, an RSVP message 37 is generated and sent toward thedestination endpoint in operation 86.

Outbound Admission Control

The RSVP reservation message 37 generated in operation 86 iscommunicated along a potential media flow path 35 toward the intendeddestination endpoint. All the routing devices along the RSVP path 35create media path state to be able to perform the admission controloperation for the media call initiated by subscriber 22. In thisexample, the RSVP proxy 38 in the border router 36 acts as thetermination point for the RSVP path 35. The RSVP proxy 38 then operatesas a second stage of outbound admission control for the media call.

For example, based on a Service Level Agreement (SLA) between serviceprovider networks 14 and 16, the RSVP proxy 38 in the border router 36might only be able to accept a predetermined number of connections, or alimited amount of bandwidth for media over link 50. Accordingly, theRSVP proxy 38 denies any RSVP connection requests 37 that would increasethe current number of connections, or exceed the bandwidth consumptionon link 50 above the pre-agreed upon limit. Thus, admission control isnot only provided for inbound calls at edge router 26, but also providedfor outbound calls going from the border router 36 to other serviceprovider networks. This ensures that the utilization of media traffic onthe link 50 remains within the SLA for the outbound link from network 14to network 16.

When the RSVP reservation 37 fails at the RSVP proxy 38 in the borderrouter 36, an admission control failure message 37 is sent back to theedge router 26 which in turn controls the gate-set. For example, whenthere is not enough capacity on the link 50, the RSVP proxy 38 may sendan RSVP failure message 37 back to the RSVP proxy 28 in operation 88.Similarly, if there is insufficient capacity on any of the links on themedia path between the border router 36 and the edge router 26, thiswill cause a reservation failure message 37 to be reported back to theedge router 26.

The edge router 26 in operation 90 accordingly sends a call failuremessage 33 back to the signaling proxy 30. The QoS control messages 33(e.g., PCMM messages) which initiated this cascade of events are knownby the signaling proxy 30. Accordingly, the signaling proxy 30 can takethe failure as a policy input to either proceed anyway only with QoS foraccess network 20, try again with a different traffic classification, orgive up and divert the call to a PSTN gateway.

If sufficient capacity exists at inter-network link 50, the RSVP proxy38 sends an RSVP RESV message back along RSVP path 35 and attempts toreserve the necessary network resources on the path 35. If there issufficient capacity, the RSVP message arrives back at the edge router 26in operation 88. The edge router 26 then accordingly sends a QoS successmessage 33 back to the signaling proxy 30 (via the policy server 32) inoperation 92. The signaling proxy 30 then proceeds with the callsignaling, which enables the subscriber 22 to start sending mediapackets over media path 24 through service provider network 14. All ofthe media packets transferred over media path 24 are now QoS controlledvia the previously exchanged RSVP messages 37.

Dynamic Call Rerouting and Call Fallback

Another advantage of the system described above, is increasedreliability. In a conventional SBC architecture, when the SBC goes down,all calls that extend over the interconnect managed by the SBC areterminated. The present system can automatically reroute a media callalong an alternate path when a primary media path fails. When no mediapaths in the service provider network 14 are available, the media callcan be automatically rerouted via a PSTN fallback path to thedestination endpoint.

Referring to FIG. 4, the previous RSVP messaging 37 between RSVP proxy28 and RSVP proxy 38 may initially be denied or fail during the mediacall. This can be due to any variety of reasons, including a hardware orsoftware failure; or an over capacity problem 98 in border router 36,inter-network link 50, or some intermediary network device in media path35. The RSVP protocol operating in network 14 can then automaticallyreestablish the QoS state and reestablish admission control along a newmedia path 100 that, in this example, terminates at boarder router 40.

The RSVP automatically moves the QoS reservation to the new path, forexample, when changes in BGP routing cause the media path to move to adifferent interface. This functionality is not currently supported incurrent SBC architectures and prevents the media call on media path 24from continuing when there is a change in the border router.

When there is no media path in network 14 that can successfully completethe media call with the required QoS, the signaling proxy 30 may thencause the subscriber 22 to establish a fallback call 102 over the PSTNaccess network 20 to the destination endpoint. Or if possible, the mediacall may be established over service provider network 14 with a lowerQoS class.

Another interesting aspect of the access control scheme is that themedia path 24 can be dynamically redirected in service provider network14 without cooperation by service provider network 16. This is madepossible by terminating the RSVP session at the RSVP proxy in the borderrouter 36 or 40.

The access control scheme can also be used in combination withMulti-Topology Routing (MTR) that provides different routing topologiesfor different services. This is another function that is not supportedin SBCs. The MTR provides separate routing for different classes ofmedia traffic (e.g. voice, video) within the service provider network 14and ensures routes to other service providers via the class-specificSLAs as part of the corresponding topology.

Media Calls Originating Other Service Provider Networks

The examples in FIGS. 1-4 describe the situation where the media calloriginates from a subscriber 22 connected to service provider network 14and is then either routed to another endpoint in network 14 or to anendpoint in another service provider network 16. FIG. 5 shows oneexample of how the service provider network 14 handles incoming mediacalls originating on an external service provider network.

Referring to FIGS. 1 and 5, in operation 120 the signaling proxy 30receives call signaling 43 from an external network. In this example,the call signaling 43 is received from service provider network 16. Thecall signaling 43 identifies the destination for the incoming call. Inthis example, the incoming call is directed to subscriber 22. Inoperation 122, the signaling proxy 30, operating in conjunction with thePolicy Server 32, identifies the edge router 26 associated with theidentified call destination. The signaling proxy 30 in operation 124exchanges QoS control messages 33 with the identified edge router 26using PCMM, or some other QoS control messaging scheme.

When appropriate in operation 126, the edge router 26 triggers the RSVPproxy 28 to conduct QoS reservation for an outbound media path used bysubscriber 22 to communicate back with the media call received fromnetwork 16. If the QoS reservation is successful, the signaling proxy 30receives a QoS success message 33 back from the edge router 26 inoperation 128. The signaling proxy 30 in operation 132 relays a callsuccess message over signaling path 43 back to the signaling proxy 44for completing the media call. The QoS control messages 33 from the edgerouter 26 may alternatively indicate QoS reservation was unsuccessful,or that only a lower QoS is available. In operation 130, a failure, orqualified signaling success message 43 is then sent by the signalingproxy 30 to signaling proxy 44.

If the in-bound media packets are coming in through the same directionas the out-bound packets from subscriber 22 are leaving provider network14, the border router 36 that contains the termination RSVP 38 for theoutbound media packets can also perform admission control and provide aQoS reservation for the incoming packets for the same media call.

Access and Reservation Control Across Different Service ProviderNetworks

In an alternative embodiment shown in FIG. 6, coordinated QoS isprovided across Autonomous System (AS) boundaries. Multiple differentservice provider networks may support RSVP and RSVP proxy. In thisconfiguration, RSVP reservations, instead of being terminated in theRSVP proxy of the border router, flow across the interconnection 50between the two service provider networks 14 and 16. This still allowsthe different service provider networks 14 and 16 to control QoS, sincethe RSVP reservation is not coming from subscribers but alternativelycoming from trusted RSVP proxies operated by the service providernetworks 14 and 16.

In the previous configuration shown in FIG. 1, the RSVP reservation wasterminated at the RSVP proxy 38 running on the border router 36. Thus,the associated RSVP reservation messages 37 were not communicated acrosslink 50. However, when the two service provider networks 14 and 16 aredirectly connected together, the existence of an SLA at the peeringpoint may be exploited to allow RSVP to flow across link 50. Forexample, instead of a proxy-RESV message terminating at the borderrouter 36, the SLA is configured to allow RSVP messages 104 into serviceprovider network 16.

For example, the subscriber 22 may initiate a media call in the samemanner described above in FIG. 1. The signaling proxy 30 exchanges thesame QoS control messaging 33 with the edge router 26 using, forexample, PCMM or DQoS. The edge router 26 uses information from thecontrol messages 33 to initiate RSVP reservation messages 104 along apossible media path for the media call. However, instead of terminatingat the border router 36, the RSVP messages 104 are transferred over link50 to service provider network 16. The RSVP messages 104 continue thoughservice provider network 16 toward the destination subscriber 112.

The RSVP messages 104 terminate at the RSVP proxy 108 in edger router106. If the requested QoS in the RSVP message 104 is successfullyallocated through the inter-network path between edge router 26 and edgerouter 106, the RSVP proxy 108 sends a ResV success message 104 back tothe RSVP proxy 28. The edge router 26 then sends access controlmessaging 33 that directs the signaling proxy 30 to enable thesubscriber 22 to start sending media packets over the QoS controlledmedia path 114. The reservation for the media flow in the oppositedirection is handled identically with the roles of the RSVP proxy 108and 28 reversed.

The RSVP messages 104 might not be forwarded over link 50 in the sameway the RSVP messages are transported inside service provider network14. Instead different mechanisms may be used to provide the necessaryassurances that the RSVP messages 104 sent across the service providernetwork boundaries are authorized. For example, an RSVP integrity objectmay be sent in the RSVP messages over link 50 that containscryptographic proof that the message was forwarded by border router 36based on a shared secret coupled to the SLA. The RSVP integrity objectis then used to authenticate and authorize the RSVP state. This has theadvantage of efficiency and exploiting native RSVP security methods.

Tunneling may also be used for aggregating RSVP to create a one-hoptunnel over link 50 for transporting the SLA-specific RSVP messages 104.This has the advantage of tying the RSVP easily to the specific peeringSLA. Tunneling of RSVP also can be extensible to transit scenarios wherethere are one or more intermediary service providers in tandem betweenthe two cooperating providers 14 and 16.

Thus, general-purpose admission control functions in edge and borderrouters are combined with media path QoS control to satisfy many of themedia-path QoS requirements in the service provider network. Existingrouting and admission control systems, such as, existing PCMM and RSVPschemes are leveraged to provide accurate capacity-based admissioncontrol for the access network, the backbone service provider network,and the interconnect peering links to other service providers. Thescheme also has the additional advantage of responding gracefully torouting changes without dropping media calls.

Multiple points of IP interconnect are supported between subscribers anda particular service provider network and between different serviceprovider networks. For example, the RSVP proxy can operate in multipledifferent edge routers and border routers in the same service providernetwork. The same or multiple different signaling proxies can then beused in the service provider network for triggering the different RSVPproxies.

The IP interconnects can support multiple services such as voice, videoand data and provides a logical separation for the interconnectedservices. For example, the different types of data can be routeddifferently and can have different QoS and different policy. Bandwidthcan be assigned on a service by service basis and traffic can be steeredwithin a service to a particular interconnect point based on availablecapacity. Call admission control can also be based on availableinterconnect capacity. For example, a peering SLA with another ISP canbe controlled based on a particular amount of data traffic and admissioncontrol can prevent the establishment of a new IP session if the sessionwould exceed the agreed upon bandwidth.

The system described above can use dedicated processor systems, microcontrollers, programmable logic devices, or microprocessors that performsome or all of the operations. Some of the operations described abovemay be implemented in software and other operations may be implementedin hardware.

For the sake of convenience, the operations are described as variousinterconnected functional blocks or distinct software modules. This isnot necessary, however, and there may be cases where these functionalblocks or modules are equivalently aggregated into a single logicdevice, program or operation with unclear boundaries. In any event, thefunctional blocks and software modules or features of the flexibleinterface can be implemented by themselves, or in combination with otheroperations in either hardware or software.

Having described and illustrated the principles of the invention in apreferred embodiment thereof, it should be apparent that the inventionmay be modified in arrangement and detail without departing from suchprinciples. I claim all modifications and variation coming within thespirit and scope of the following claims.

1. A system for establishing media calls, comprising: a networkprocessing device operating a Resource ReSerVation Protocol (RSVP) proxythat controls flow admission and Quality of Service (QoS) for a mediacall in a service provider network.
 2. The system according to claim 1wherein control messaging received from a signaling proxy or policyserver triggers the RSVP proxy to conduct QoS reservation over theservice provider network.
 3. The system according to claim 2 wherein thecontrol messaging uses PacketCable Multi-Media (PCMM) and/or DynamicQuality of Service (DQoS) messages.
 4. The system according to claim 2wherein the network processing device initiates QoS reservation thoughthe service provider network to an RSVP termination point and notifiesthe signaling proxy to complete the media call when the RSVP terminationpoint indicates successful QoS reservation along the media path.
 5. Thesystem according to claim 4 wherein the QoS reservation is establishedover routes computed by Multi-Topology Routing (MTR) according to aparticular media class associated with the media call.
 6. The systemaccording to claim 4 wherein the RSVP termination point is located in anedge router in another service provider network.
 7. A network processingdevice, comprising: a signaling proxy receiving media call signaling andusing information from the media call signaling to trigger a ResourceReservation Service Protocol (RSVP) proxy to reserve QoS along a mediapath in a packet switched network.
 8. The network processing deviceaccording to claim 7 wherein the signaling proxy is a Session InitiationProtocol (SIP) or H.323 proxy that uses Packet Cable Multi-Media (PCMM)and/or Dynamic Quality of Service (DQoS) messages to trigger the RSVPproxy.
 9. The network processing device according to claim 7 wherein thesignaling proxy enables the media call when a control message isreceived back from the RSVP proxy indicating QoS is successfullyreserved along the media path.
 10. A system for managing Quality ofService (QoS) for media calls in a service provider network, comprising:a signaling proxy receiving call signaling for the media calls andgenerating corresponding control messages; and an edge router initiatingQoS reservation along a media path in the service provider network inresponse to the control messages received from the signaling proxy. 11.The system according to claim 10 including a border router located inthe service provider network linked to another service provider network,the border router receiving the QoS reservation from the edge router andsending back a QoS reservation success message when the requested QoSreservation can be provided over the link with the other serviceprovider network.
 12. The system according to claim 10 wherein: the edgerouter enables the signaling proxy to connect the media call when theQoS is successfully reserved over the media path to the border router;and the edge router causes the signaling proxy to disconnect the mediacall, reroute the media call over another media path in the serviceprovider network or in an access network, or establish the media callwith a lower QoS when the QoS reservation fails over the media path tothe boarder router.
 13. The system according to claim 10 wherein theedge router uses Multi-Topology Routing (MTR) to provide differentrouting topologies for different media services.
 14. The systemaccording to claim 10 including a policy server coupled between thesignaling proxy and the edge router for enforcing access policies formedia calls received by the signaling proxy.
 15. A method forcontrolling media connections over a network, comprising: receivingQuality of Service (QoS) control messages identifying an access networkQoS; and using the access network QoS control messages to triggerResource Reservation Service Protocol (RSVP) reservation over a serviceprovider network.
 16. The method according to claim 15 including usingthe RSVP reservation to control outbound access from the serviceprovider network to another service provider network.
 17. The methodaccording to claim 15 including using PacketCable Multi-Media or DynamicQuality of Service (DQoS) messages to trigger the RSVP reservation overthe service provider network.
 18. The method according to claim 15including using the QoS control messages to direct a signaling proxy toenable a media call.
 19. The method according to claim 15 includingsending the RSVP reservation though the service provider network to anRSVP proxy termination point in another service provider network andenabling a media call when the QoS identified in the QoS controlmessages is successfully reserved through a media path to the RSVP proxytermination point.
 20. The method according to claim 15 includingestablishing routes computed by Multi-Topology Routing (MTR) accordingto a particular media class associated with the media call andconducting the RSVP reservation along the established routes.
 21. Asystem for controlling media connections over a network, comprising:means for receiving Quality of Service (QoS) control messagesidentifying an access network QoS; and means for using the accessnetwork QoS control messages to trigger Resource Reservation ServiceProtocol (RSVP) reservation over a service provider network.
 22. Thesystem according to claim 21 including means for using the RSVPreservation to control outbound access from the service provider networkto another service provider network.
 23. The system according to claim21 including means for using PacketCable Multi-Media or Dynamic Qualityof Service (DQoS) messages to trigger the RSVP reservation over theservice provider network.
 24. The system according to claim 21 includingmeans for using the QoS control messages to direct a signaling proxy toenable a media call.
 25. A computer storage medium containinginstructions for controlling media connections over a network, theinstructions when executed comprising: receiving Quality of Service(QoS) control messages identifying an access network QoS; and using theaccess network QoS control messages to trigger Resource ReservationService Protocol (RSVP) reservation over a service provider network.